Changes contribute to better code readability and easier
understandable msgid's - good for translators, as Jun Omae suggested.
Please see #8063 for details.
I took the chance to finally remove a leftover from changeset [4638].

This causes minor changes to i18n, as one msgid is split into two.
A new message catalog has been extracted and corresponding msgtxt's
of existing translations have been fixed accordingly. Pending fix for
one German translation is merged as well.
Thanks to Jun Omae for reporting the issue and suggesting template changes.

Replacements (%s) are rewritten with named variables like %(variable)s.
This helps a lot when translating without looking at the source code.
Thanks to Jun Omae for both, suggestion and providing actually better code.